Apparatus for analyzing a gas



Nov. 14, 1939. P. T. SPRAGUE ET AL 2,180,322

APPARATUS FOR ANALYZING A GAS 2 Sheets-Shet 1 Filed June 4, 1937 F/cv. Z

INVENTORS. JPEAGUE.

w 'l BY PH/L/P 7' ATTORNEYS.

1939. P. T SPRAGUE -r AL APPARATUS FOR ANALYZING A GAS Filed June 4, 1937 2 Sheets-Sheet 2 I Patented Nov. 14, 1939 UNITED STATES APPARATUS FOR ANALYZING A GAS Philip T. Spraguc and Charles A. Sprague, Michigan City, Ind.

Application June 4, 1937,. Serial No. 146,452

6 Claims.

This application relates to method and means for determining carburetor adjustment, and particularly to method and means of this character involving analysis of exhaust gas to determine the relative percentages of certain constituents thereof by which the operating efficiency. of the engine tested may be calculated as a basis for determining the carburetor adjustment necessary in that engine.

It is known that the efiiciency of operation of an internal combustion engine depends in part upon the air-fuel ratio governed by the carburetor. It is further known that the composition of the exhaust gas varies in definite relation to the ratio of air-fuel input. Thus, there is a definite relation between such constituents of exhaust gas as CO2, CO, H2, and 02 for any given air-fuel ratio supplied by the carburetor. It is therefore possible, by accurate analysis of the percentage or quantity of any two constituents of exhaust gas, to quickly determine whether the air-fuel ratio is too rich or too lean. Such determination is particularly valuable and accurate where the two constituents are determined from the same sample of exhaust gas to avoid possibility of variations in engine operation during the interval between which separate samples are taken.

It is therefore the primary object of this invention to provide means whereby simultaneous determination of the relative percentage of two constituents of a gas may be obtained.

A further object is to provide a novel and simple method of this character requiring only a short time for obtaining the desired result.

A further object is to provide a novel method for rapidly determining whether ignition is taking place in all cylinders of an engine during engine operation.

A further object is to provide novel means for.

analyzing a gas sample.

A further object is to provide a device of this character having a pair of gas analyzing members arranged for simultaneous operation and connected with means for simultaneously supplying part of the same gas sample to each memher, and juxtaposed indicators each controlled by one of said members.

A further object is to provide means of this character by which an exhaust gas sample may be analyzed to simultaneously measure the carbon dioxide constituent and the combined carbon dioxide and oxygen constituents thereof.

A further object is to provide a method of this character wherein the amount of a certain constituent of an exhaust gas is determined by the difference in measurement between the combination of that constituent combined with another constituent, and the other constituent alone.

Other objects will be apparent from the description and the. appended claims.

In the drawings:

Fig. 1 is a rear elevation of our improved device in sampling position, with parts shown in section.

Fig. 2 is a rear elevation of our improved device in testing position. Fig. 3 is a horizontal sectional view of the device taken on line 33 of Fig. 1.

Fig. 4 is a front elevational view of the device illustrating the double indicating pointer arrangement.

Fig. 5 is a graph illustrating the accepted relationship between exhaust gas composition and air-fuel ratio.

Fig. 6 is a fragmentary detail sectional view of the gas sampling means.

Fig. 7 is a fragmentary horizontal transverse sectional view illustrating a modified construction of the device with the absorbing units in sampling position.

Fig. 8 is a schematic view of a modified construction of gas analyzing unit in sampling position.

Fig. 9 is a schematic View of the modified gas, analyzing unit in absorbing or testing position.

Referring to the drawings, which illustrate the preferred embodiment of our invention, the numeral l0 designates a casing of any suitable size and shape having a sight opening H to expose a scale l2 positioned transversely and vertically within casing II] in rearwardly spaced relation to the front wall of the casing and opposite sight opening ll. Scale l2 includes suitable indicia [3 arranged in arcuate relation thereon toindicate the result of gas analysis in any desired 1 manner, as by volumetric percentage.

Within casing III are secured spaced brackets M, to each of which is pivoted at l5 a gas analyzing unit l6 of the tiltable type as for instance that forming the subject matter of the application of P. T. Sprague et al., Ser. No. 711,982, filed February 19, 1934. As here illustrated, and best shown in cross section in Fig. 1, each of the units may comprise a housing I! formed of any suitable material and of approximate U-shape providing a gas absorbing chamber l8 containing a gas absorbing agent in one leg, a gas measuring chamber IS in the other leg, and a chamber 20 between said first named chambers. Thedevice is normally positioned at an angle as illustrated in Fig. 1 so that mercury or other inert fluid material or liquid will fill chamber 20 to the level of the bottom of gas measuring chamber iii. A gas intake conduit 2| connects with the chamber 19 adjacent the lower end thereof. A conduit 22 extends from the upper end of chamber l9 to a position above chamber It; a conduit 23 having a capillary bore branches from conduit .22 and extends into chamber l8 in communication therewith; a conduit 24 branches from conduits 22 and 23 and extends downwardly along the outer side of chamber 18; and a conduit .225 communicates with all the aforementioned conduits opposite conduit 23 and extends upwardly therefrom. Conduits 22, 23 and 2 are preferably Iigid, whereas conduits 2i and 25 are preferably flexible, at least in part, for purposes to be hereinafter set forth. Each of these houslugs 11 is connected to bracket M at pivot if: at substantially the center of said housings. A cupshaped member 26 open at its upper end is fixedly carried by each housing I! at the outer side of chamber l8 thereof, and contains a quantity of mercury or other inert fluid. The lower end of conduit 24 extends into cup 2 5 with its end spaced slightly above the bottom thereof.

The units iii are interconnected by a link 2'! pivoted at its ends at 28 to said units in corresponding or identical relation. A reciprocable rod 29 substantially vertically positioned is pivoted at 30 at its lower end to one side of one unit I t, and its upper end terminates in a head 3% positioned exteriorly of casing Ml.

A gas supply conduit 32 of any suitable length extends into casing I'll in any suitable manner from the exterior thereof and connects withthe center leg 33 of a T-shaped fitting suitably supported in the upper end of housing ID by a bracket 34. The aligned cross legs 35 of the T-shaped fitting have the fiexible conduits 2| from the respective units It connected therewith.

A bracket 36 is secured to the top of casing ID at the center thereof and carries an arbor 31 on which two pointer arms 38 are pivoted in spaced relation to their upper ends. The pointer arms 38 are positioned adjacent the front wall of casing it and terminate adjacent indicia l3 in forwardly spaced relation to scale I 2. The upper ends of the pointer arms are pivotally connected to the ends of links 39 extending substantially horizontally and laterally for pivotal connection with the respective upper ends of substantially vertical arms 40 which are carried by a pair of suitable metal bellows or Sylphons GI mounted on brackets 2 at the side of casing Ill. The flexible tube 25 from each unit I6 is connected with one of the Sylphons 4|.

To use the device, the units It are positioned as illustrated in Fig. 1 by manipulation of rod 29, said units moving together by means of interconnecting link 21 and preferably being provided with suitable means (not shown) for limiting their movement in clockwise direction as viewed in Fig. 1 beyond a tilted or angular position substantially as shown. A gas sample is introduced into supply conduit 32, and. passes therethrough to be divided by the T-shaped fitting with which conduit 32 and the corresponding conduits 2| of the two units l6 are connected. The divided gas sample thence enters and fills the gas measuring chamber l9 from which it exhausts through conduits 22 and 2d to atmosphere. Thus portions of the identical gas sample pass to and through each unit IS; The capillary character of bore of conduit 23, together with the fact that the said conduit has no exhaust except at its outer end through the conduits from which it branches, substantially prevents absorption of the gas during the time the units are in the sampling position illustrated in Fig. 1.

When a sufiicient quantity of the gas has been passed through units It to insure exhaust therefrom of gases previously contained thereby, the rod 23 is depressed to pivot the units simultaneously and equally to the absorbing on analyzing position illustrated in Fig. 2, there preferably being provided suitable stop means (not shown) to limit the pivotal movement of the units in counterclockwise direction as viewed in Fig. 2. When the units EB are in this absorbing position, the mercury enters and fills chamber is, thereby closing the conduit 2i of each unit and forcing the gas from the measuring chamber l9 through conduits 22 and 23 to absorption chamber l3. At the same time, the mercury in cup part 26 is shifted to immerse the lower end of conduit 24, whereby both the intake and exhaust ends of the normal gas passage of the device are closed by shifting of the two mercury bodies of each unit. In this way a definite volume of gas is trapped and forced into the absorption chamber l8 whose liquid level has lowered by shifting of the mercury into chamber l9. As the gas absorption occurs, a reduction in pressure results which actuates the respective Sylphons H connected thereto by conduits 25 and thereby shifts arms 4i! and levers 359 to pivot pointer arms 38 relative to scale l2 whose indicia I3 is callbrated for the units.

In order to achieve the desired result of determining carburetor adjustment from operation of the device it is necessary that the results of the operation of the two units indicate on the scale the percentage of two of the constituents of the exhaust gas. Fig. 5 is a chart showing computed relationships of exhaust gas composition and airfuel ratio. Thus it will be seen that Hz and CO decline rapidly to. zero as air-fuel ratios increase to 14.7, beyond which point neither occurs; and that 02 is zero at and below an air-fuel ratio of 14.7 and increases rapidly as air-fuel ratios exceed 14.7. The CH4. constituent remains substantially constant throughout the whole working range of air-fuel ratios. The CO2 constituent increases rapidly as air-fuel ratio progresses from its low limit to 14.7, and thereafter declines less rapidly as air-fuel ratio exceeds 14.7. These relationships are based on a fuel composition of Cal-I17, water reaction quilibrium constant of 3.8, and formations of 0.15 mol. CH4 per mol of Cal-I11 burned.

From the above it will be obvious that it becomes desirable to measure the CO2 constituent and one of the following constituents H2, CO or 02. CO2 is readily absorbed by KOH and hence we prefer to supply one of the units l6 with KOH as an absorbing agent. With CO2 thus definitely determined, we prefer to use an absorbing agent which will absorb both CO2 and 02 substantially as rapidly as KOH absorbs CO2, and we have found that the absorbing agent known commercially as SeezOz and forming the subject matter of the patent application of Dorothy Quiggle, Serial No. 35,397, filed August 8, 1935, is most satisfactory for this purpose. Where this absorber is used in the second unit I 6, the pointer arms 33 indicate respectively the CO2 content and the combined CO2 and 02 contents, so that the difference in the positions assumed by the two pointer arms constitutes the O2 constituent. It

will, of course, be obvious that the above absorbing agents, while preferred because of various factors such as substantially similar time required for absorption, rapidity of absorption, and direct absorbing action, may be replaced by any other agents found to serve with equal facility. For instance, pyrogallic acid will absorb both CO2 and O2, and may be used if desired; but we find that it lacks both the capacity for and rapidity of absorption present in SeezOz.

Using the absorbing agents above mentioned the following results have been obtained. Where air-fuel ratios are below 14.7, the free oxygen content of the exhaust gases will not exceed 0.5 if all of the spark plugs are firing; and above 14.7 the oxygen content follows the chart in Fig. 5 when all plugs are firing. It will thus be seen that where the 02 content is at or below 0.5, the air-fuel ratio is too rich unless a maximum value of CO2 according to the chart is concurrently obtained; and the approximate air-fuel ratio can be determined from the chart. For instance, with 02 at or below 0.5 and CO2 at 12, an air-fuel ratio of about 13.1 is indicated. Likewise, an 02 content above 0.5 and a C02 content above 11 indicates a lean mixture. In this connection it has been found that, if one or more of the spark plugs do not fire, an 02 content above 0.5 will be obtained, but in no such instance will the CO2 content exceed 9. Therefore a high 02 content and low CO2 content designates failure of ignition in one or more cylinders of the engine. In this way, by the practice of the method as above outlined, it is possible to determine, simultaneously and automatically, factors of exhaust gas condition which accurately indicate the air-fuel ratio supplied by the carburetor and whether and to what extent the same needs adjustment. The reading obtained by this method also immediately shows any failure of ignition and combustion in any cylinder of the engine. To the best of our knowledge, this method and apparatus constitutes a substantial advance in the art by reason of its accuracy, simplicity, rapidity and wide range of derived information.

A slightly modified embodiment of the device has been illustrated in Fig. '7 which has the advantage of compactness. In this construction the units l6 are rigidly mounted, side-by-side on the same shaft 55, which is journaled in brackets M. The device is similar to the preferred embodiment in all other respects.

While the construction of the absorbing units i6 as hereinbefore described is preferred, the same may be slightly altered if desired to reverse the position of gas intake and exhaust as illustrated schematically in Figs. 8 and 9. The parts of this modified analyzer are designated by the same reference numerals as in the preferred form. Thus casing i'l contains chambers i8, I9 and 2B of the same arrangement and purpose as in the preferred embodiment. Conduits 22, 23 and 25 remain the same in construction and arrangement. Gas exhaust conduit 24 is connected with the casing at the lower end of chamber l9, however. Furthermore the external mercury containing chamber 28 is entirely closed and sealed as by a top 50. Conduit 5i branching from conduits 22, 23 and 25 terminates within closed chamber 26 in slightly spaced relation above the bottom of said chamber. Gas supply conduit 2! enters closed chamber 26 and preferably terminates a substantial distance above the chamber bottom to be clear of the contained mercury in all operative positions of'ithe device; and a gas exhaust conduit 52 is positioned opposite conduit 5I' terminating at one end in slightly spaced relation above the bottom of chamber 26 and open to atmosphere at its other end.

Fig. 8, the mercury in chamber 26 shifts to close conduit 5i and open conduit 52, while the mercury in housing i fills chamber l9 and closes exhaust conduit 24. The gas thereby trapped constitutes a sample of known volume which is forced into absorbing chamber l8 by the mercury as in the preferred form of unit. At the same time, gaswhich continues to enter chamber 26 from conduit 2| is exhausted or shunted to atmosphere through conduit 52.

It will be obvious that the apparatus is susceptibleof other changes without departing from the spirit of the invention. Thus, for example. various types of indicating devices are common in the art and may be employed in place of the Syphon-actuated pointers, included among which is the liquid column type of indicator which is bbviously readily adaptable to the instant device.

We claim:

1. In a gas analyzer, a tiltable unit including a casing containing a gas absorbing agent, a gas measuring chamber, a sealed chamber containing an inert fluid, a gas passage including conduits leading to and from both of said chambers, a by-pass between said passage and casing, means for filling said measuring chamber with inert fluid to transfer gas in said measuring chamber to said casing and seal one conduit communicating with said measuring chamber upon tilting of said unit, said first named fluid sealing one of the conduits entering said sealed chamber upon said tilting, and means for measuring the extent of gas absorption in said casing.

2. In a gas analyzer, a tiltable unit including a casing containing a gas absorbing agent and a pair of sealed chambers, a gas passage including a conduit connecting said chambers and a pair of conduits each communicating with one chamber, a by-pass from said first conduit to said casing, means actuated by gravity upon tilting of said unit to close one of the conduits communicating with each chamber, said means serving to expel gas in at least one chamber into said casing, and means for measuring the extent of gas absorption in said casing.

3. In a gas analyzer, a tiltable unit comprising a casing containing a gas absorbing agent, a gas measuring chamber and a sealed chamber, a gas supply conduit communicating with said sealed chamber, a conduit connecting said chambers and having a b-y-pass communicating with said casing, an exhaust conduit communicating with the lower end of said measuring chamber, means acher in one leg, the other leg containing a gas absorbing agent, mercury filling the base of the chamber, a sealed chamber carried by said housing and containinga quantity of mercury, a gas supply conduit communicating with said sealed chamber, a conduit connecting the upper end of the empty chamber with the opposite housing leg and with said sealed chamber and terminating above the normal mercury level in the latter, an exhaust conduit extending from the lower end of the upper chamber, the mercury in said housing filling said empty chamber to close said exhaust conduit and force the gas in said chamber into the opposite housing leg and the mercury in said sealed chamber immersing the end of said connecting conduit upon tilting of said unit, and means for measuring the extent of gas absorption following said tilting.

5. The combination with a tiltable gas analyzer having measuring and absorbing chambers connected at top and bottom respectively and separated at the bottom by an-inert liquid adapted to enter the measuring chamber to force gas therefrom to said absorbing chamber upon tilting, of a gas supply system comprising a sealed chamber carried by said analyzer and containing inert liquid, a gas supply conduit communicating with said sealed chamber, and a conduit branching from said top connection and terminating above the normal liquid level in said sealed chamber, said liquid shifting to seal said last named conduit upon tilting of said analyzer.

6. The combination with a tiltable gas analyzer having measuring and absorbing chambers connected 'at top and bottom respectively and separated at the bottom by an inert liquid adapted to enter the measuring chamber to force gas therefrom to said absorbing chamber upon tilting of a gas supply system comprising a sealed chamber carried by said analyzer and containing inert liquid, a gas supply conduit communicating with said sealed chamber, a conduit branching from said top connection and terminating in said chamber at one side thereof and above the normal liquid level therein, and a by-pass at the other side of said sealed chamber normally immersed in the liquid at its lower end and open to atmosphere at its opposite end, said liquid shifting to open said by-pass and immerse said branch conduit upon tilting of said analyzer.

PHILIP T. SPRAGUE'. CHARLES A. SPRAGUE. 

